Is it really necessary to use premium gas in a 2004 Eclipse GTS?


Asked by May 16, 2007 at 10:34 AM about the 2004 Mitsubishi Eclipse GTS

Question type: Maintenance & Repair

I have recently purchased the GTS and since the gas prices have gone through the roof, I was wondering if it was necessary to use Premium? What octane should I not go below?

12 Answers


I think its only recommended that you use premium, not required.

1 out of 1 people think this is helpful.

you will get better gas milage and your car will run smoother if you use it

2 out of 2 people think this is helpful.

If the GTS's V6 is designed for premium (which if i remember correctly, it is), you should stick with that. Basically there's a certain quality level in premium fuel, and if you drop down, you'll start wearing the fuel system out. also, the engine's made to run on premium so you wont get as good of gas mileage and power. Stepping up in octane is always good, but avoid stepping down if possible.

4 out of 4 people think this is helpful.

They recomend running premium because of high compression. It keeps the motor from predetonation or "knocking" or "Pinging". Too much knocking will end up wearing the motor out. As far as gas miliage.. I have never noticed or heard of a significant difference between regular or premium. So its good to go higher octane. 10 gallons at $3.30 for regular = $33 10 gallons at $3.50 for premium = $35 $2 every fill up isnt bad for a relyable motor.

8 out of 8 people think this is helpful.

Generally speaking the octane ratings are higher than advertised. That is a 'minimum' rating after all. However, that being said the comments on pre-detonation wearing out the engine or damaging the valve train are true. Another trouble may be incomplete combustion, which can cause run-on after you turn off the engine (less common but not unheard of in FI engine). Also wears out the engine because the revs drop way down and cylinders fire unbalanced causeing uneven strain on the rotating assembly. My opinion would be not to drop below 89 octane in your car requests 91. Granted I would recommend the 91 just because they generally have more ditergants in them and keep your valves from sticking in the long run.

3 out of 3 people think this is helpful.

i have an 03 eclipse GT and i put plus in my car. it runs great! but prices suck. lol


remember one thing.. when you use a lower than recommended octane fuel in a high compression engine, several things happen. 1 the timing will retard because the knock sensor senses engine ping. Thus.. 2 , lower power, 3, rough idle, 4, mpg will decrease. Use lower octane long enough and you risk burning holes in the pistons and making a mess of the valves

1 out of 1 people think this is helpful.

I am so upset. I have a Mitshibushi 2003 Eclipse GTS V6. My husband said you don't necessarily need premium but can use unleaded. Now the darn thing is running rough. I have a check engine light on and took it into a mechanic and he said I have a vacuum leak and its runs rough and sounds terrible when starting up but not in a minute, it stops and runs smooth. Mechanic said it would cost around $1,600 to fix. I love this car! Ugh, I am never going to listen to him again, When I had premium in there I had no problems....................

3 out of 3 people think this is helpful.

We have Mitsubishi Endeavor 2005, since 2006. It requires premium gasoline which I must use it or damage to engine could be severe. Next time before buying another vehicle I will be looking in owner manuals first. It hurts a lot at gas pumps. I wouldn't buy next vehicle which required premium gasoline, no matter what. I tried using lower grade but it ended using more gas.

Its good to have high octane only if your car needs it,most cars are now engineered to run on basic fuels.The issue is that using cheaper fuels will contain moisture and less detergents that help clean the engine.Higher octane fuel contains more detergents and increases the ignition timing which might reduce knocking on certain cars.It might also slightly give you better mileage but it will not give you better mileage that what your car originally gave you when it was new. It will MAINTAIN that mileage.As long as you don't go lower than what the manufacturer recommended in octane levels you will be fine.Good luck


I have an 02 gt that recommends premium fuel and I have used both and the only difference that I have noticed is that the high end performance is slightly reduced running 87 octane .

1 out of 1 people think this is helpful.

higher octane = longer explosion burn time which pushes on the piston longer and increases power and mileage. Shorter explosion time damages parts over time. I can get 35+ mpg on the highway easily with premium.

Your Answer

Add photo

Related Questions

  • mitsubishi eclipse spyder gts common transmission problems 12 answers

    mitsubishi eclipse spyder gts common transmission problems

    2004 Mitsubishi Eclipse GTS


    Maintenance & Repair

  • tapping noise in 2004 mitsubishi eclipse gt 1 answer

    I bout a 2004 eclipse gt with a tapping sound on the passenger side of the car in the engine bay. I assumed it was the timing chain given the high pitched type of tapping sound it was making. Well...

    2004 Mitsubishi Eclipse GT


    Maintenance & Repair

  • 98 2.0 eclipse error codes p0171/p0301 70 answers

    My daughter has a 98 mitsubishi eclipse 2.0.129,000miles she has replaced the plugs and wires, It has error codes p0171 and p0301 lean fuel, i have checked for vacuum and gasket leaks with brake clean...

    1998 Mitsubishi Eclipse GS


    Maintenance & Repair

  • Unknown fluid leak, '03 Eclipse GTS 2 answers

    I purchased a 2003 Eclipse GTS 3.0L V-6 with manual tranny, 107800 miles on it, a couple of weeks ago for my daughter to drive back and forth to college. The guy I bought it from was the 2nd owner, an...

    2003 Mitsubishi Eclipse GTS


    Maintenance & Repair

  • Gas 6 answers

    I am considering buying this veh and someone asked me about the gas and did it have to be premium or not. Well, since it's a 4 cylinder and not the V6 GT or GTS, I wouldn't think I had to, do I?

    2003 Mitsubishi Eclipse GS


    Shopping & Pricing


Looking for a Used Eclipse in your area?

CarGurus has 1,309 nationwide Eclipse listings starting at $1,950.


Search Mitsubishi Eclipse Questions

Mitsubishi Eclipse Experts

#1 dandyoun
Reputation 1,570
#2 Daniel Foster
Daniel Foster
Reputation 720
#3 Tom Demyan
Tom Demyan
Reputation 380
View All

Related Models For Sale

Used Mitsubishi Eclipse Spyder
17 Great Deals out of 597 listings starting at $2,395
Used Ford Mustang
318 Great Deals out of 45,523 listings starting at $2,000
Used Mitsubishi Lancer
23 Great Deals out of 5,438 listings starting at $1,599
Used Mitsubishi Lancer Evolution
18 Great Deals out of 572 listings starting at $13,500
Used Honda Civic
486 Great Deals out of 80,458 listings starting at $558
Used Nissan 350Z
50 Great Deals out of 1,253 listings starting at $4,250
Used Honda Civic Coupe
137 Great Deals out of 18,148 listings starting at $1,500
Used Mazda RX-8
14 Great Deals out of 356 listings starting at $1,299
Used BMW 3 Series
1,016 Great Deals out of 34,833 listings starting at $900
Used Hyundai Tiburon
5 Great Deals out of 567 listings starting at $2,495
Used Honda Accord
703 Great Deals out of 81,926 listings starting at $500

Used Cars For Sale

2012 Mitsubishi Eclipse For Sale
71 listings starting at $4,950
2011 Mitsubishi Eclipse For Sale
53 listings starting at $4,990
2010 Mitsubishi Eclipse For Sale
7 listings starting at $7,000
2009 Mitsubishi Eclipse For Sale
5 Great Deals out of 137 listings starting at $3,500
2008 Mitsubishi Eclipse For Sale
200 listings starting at $3,395